Two-in-one Soraluce milling solution for Mactaggart Scott

The installation of a large-capacity Soraluce travelling column floor-type CNC milling machine with an extensive 16 metre long bed did not only enable MacTaggart Scott to bring in-house the machining of extra-long workpieces – a move that in itself justified the machine purchase – but after expert engineering from T W Ward CNC Machinery (Ward CNC) added a second machine column onto the original machine bed, to give a double-column single-bed duplex configuration, the company was also able to enter into a new era of machining parts simultaneously at ‘both sides’ of the machine bed or, using one column, to machine very long components.

This upgrade provided excellent machining flexibility and is an efficient use of the space available in the machine shop.

Supplied six years ago by Ward CNC, the first Soraluce FL16000 was purchased by the long established (since 1898) company that focuses on the naval defence and marine industries to machine a specific component for aircraft carrier lifts. The workpieces, which were originally outsourced, were brought in-house so that MacTaggart Scott could control machining quality and costs. These particular parts occupied the Soraluce’s enormous 16 metres longitudinal traverse.

'This job alone justified the machine purchase,' says Robert Davidson, Production Engineering Manager. 'But once we realised the capabilities of the Soraluce, we knew we could start re-thinking our traditional machining routines and consider producing workpieces in a different and much more economical way.'

He continues: 'With its 4,000 revs/min universal machining head, which is indexable in 2.5 by 2.5 degree increments, we saw immense flexibility in the type and the way that workpieces could be produced.

'Then we had the Eureka moment: with such a large bed and relatively few of the 16 metre-long workpieces required, we thought ‘why not install another complete machine column and head, but one this time is configured with a 30-tool automatic toolchanger?’. The machine’s original configuration was specified for workpieces that required only minimal tool changes, since like much of our throughput the job was low volume and very bespoke and made to order.

'The idea was to install the column on the original machine bed at the side of the existing column to effectively create two x seven metre X axis travel capacity machines on one common bed so that medium-sized workpieces could be machined simultaneously on each ‘side’. The configuration also enables us to quickly revert to ‘full length’ capacity machining using one column only as and when we need it, and the two heads can operate separately and simultaneously.

He adds: 'The result of the modification was that we halved the cost of one job (another outsourced contract) by simply ‘spinning’ the part on its fixturing; and on another we halved machining times by producing the four metre long parts in one hit on the Soraluce rather than machining in two sequences on a two metre capacity machining centre (machining one end then shunting the part along to machine the other).'

Engineers from Ward CNC undertook the highly-involved modification of installing, integrating and commissioning the second column/head.

Critically, because each column and head is working on the same X axis, each column is controlled by its own Heidenhain iTNC 530 CNC with measurement feedback on all axes via Heidenhain LB382 linear scales. The machine PLC software was modified to incorporate anti-collision software for safe working functionality.

Today, the Soraluce has become one of the most heavily worked machine at MacTaggart Scott’s Loanhead, near Edinburgh site – and it continues to spur new approaches to machining a wide variety of parts in a range of materials - including a number of workpieces that were formerly fabrications. Indeed, says Mr Davidson, the first question we now always ask ourselves for every new part is ‘can we put it on the Soraluce?’

With a 28 kW main (ISO 50) spindle with two-speed ZF gearbox providing 764 Nm of torque and able to reach speeds of 6,000 revs/min, combined with and Y and Z axes travels of 1,400 mm and 1,000 mm, respectively, the FL16000 has rapid traverse rates of 35 m/min in all axes.

The H20 universal indexing heads feature air and oil lubrication and, importantly, the combination of both articulated movements means the 144 x 144 positions cover all eventualities at either end of the table.

'It is the wide range of possibilities offered by this type of machining head that really sets the machine apart,' comments Mr Davidson, who goes on to say that much of the cycle time savings being gained are achieved by applying small and fast cuts at high feed rates using carbide tooling. 'We use CNC machines for repeatability rather than speed; consistency of machining is imperative,' he adds.

The impressive specification is underpinned by a rigid machine of cast iron construction, coupled with linear guides and preloaded and pre-tensioned ballscrews in the Y and Z axes.

Ward CNC was, in fact, MacTaggart Scott’s preferred supplier of such a large capacity milling centre. 'We’ve sourced machines, particularly horizontal borers, from Ward for a number of years [including two Union BFT 130/7s, a Union BFT 130/5 and a Hyundai-Kia SKT 28LB] and are well-versed in the company’s level of support – not only in terms of new machines but also in the way the company can quickly react with cost-effective refurbished/reconditioned solutions.

'For example, on one occasion we had a failure with the head on an ageing borer – a critical machine – when the counterweight actually fell down onto and damaged the bed. Ward CNC had a similar machine onsite at its Sheffield base and this was effectively cannibalised to repair our machine, which was up and running within just six weeks. That level of service is indispensable when you are committed to such a niche market as ours.'

Commenting that 'there is not a Royal navy ship afloat that does not have a MacTaggart Scott part', the company focuses on the design, manufacture and lifetime support of mainly hydraulics equipment such as hydroplanes, mast raising equipment and lifting decks for aircraft carriers – in one case, the manufacture of a platform weighing 140-tonnes and able to carry 70-tonne (two aircraft) loads!

From initial discussions through to manufacture, the contracts are often very lengthy and of high-value: for example, for the provision of four lift units for two ships, the £13.5 million deal stretched over four years and manufacture alone took one-and-a-half years.

In support, as well as a comprehensive cell-based machining capability of milling – where the Soraluce is the focus – there is capacity for turning, boring and spline cutting up to seven feet long in super duplex stainless steel. The company’s capabilities also extend to gear shaping on a 1.8 metre diameter capacity Gleason gear shaper, plus fabrication, welding, assembly and test.

The 325-employee company also maintains a strong engineering department that utilises a range of analytical and programme management software systems such as ProEngineer CAD, stress and finite element analysis, mathematical modelling (Mathcad, Simulink, LabView), plus extensive test facilities embracing, for instance, hyperbaric chambers and various high torque/hydraulic rigs.